Adaptive impedance translation circuit

Abstract

The present invention relates to an adaptable RF impedance translation circuit that includes a first group of inductive elements cascaded in series between an input and an output without any series switching elements, a second group of inductive elements cascaded in series, and a group of switching elements that are capable of electrically coupling the first group of inductive elements to the second group of inductive elements. Further, the adaptable RF impedance translation circuit includes at least one variable shunt capacitance circuit electrically coupled between a common reference and at least one connection node in the adaptable RF impedance translation circuit, which includes control circuitry to select either an OFF state or an ON state associated with each of the switching elements and to select a capacitance associated with each variable shunt capacitance circuit to control impedance translation characteristics of the adaptable RE impedance translation circuit.

What is claimed is: 
     
       1. A first radio frequency (RF) impedance translation circuit comprising:
 a first plurality of inductive elements cascaded in series without any series switching elements between an input and an output using at least a first of a plurality of connection nodes; 
 a second plurality of inductive elements cascaded in series using the plurality of connection nodes; 
 a first plurality of switching elements, such that:
 a first of the first plurality of switching elements is coupled between a second of the plurality of connection nodes and one selected from the group consisting of the input, the output, and the first of the plurality of connection nodes; 
 a second of the first plurality of switching elements is coupled between a third of the plurality of connection nodes and another selected from the group consisting of the input, the output, and the first of the plurality of connection nodes; and 
 each of the first plurality of switching elements has one of an OFF state and an ON state based on a switch control signal; 
 
 at least one variable shunt capacitance circuit, such that each variable shunt capacitance circuit:
 is coupled between a common reference and a corresponding one selected from the group consisting of the input, the output, and the plurality of connection nodes; and 
 has a capacitance based on a capacitance control signal; and 
 
 control circuitry adapted to provide each capacitance control signal to a corresponding each variable shunt capacitance circuit and each switch control signal to a corresponding each of the first plurality of switching elements, 
 
       wherein a first impedance presented to the output is translated into a second impedance presented at the input; and further comprising 
       a common power amplifier comprising a plurality of segmented output stages coupled in parallel, such that:
 when at least one of the segmented output stages is in a DISABLED state, the common power amplifier has a first output power level and a first output impedance; and 
 when the at least one of the segmented output stages is in an ENABLED state, the common power amplifier has a second output power level and a second output impedance, 
 
       wherein the second output power level is greater than the first output power level and the second output impedance is less than the first output impedance. 
     
     
       2. The first RF impedance translation circuit of  claim 1  wherein the input is adapted to receive an RF input signal and the output is adapted to provide an RF output signal based on the RF input signal, wherein impedance translation characteristics of the first RF impedance translation circuit are based on each capacitance control signal and each switch control signal. 
     
     
       3. The first RF impedance translation circuit of  claim 2  further comprising at least one plurality of inductive elements cascaded in series using the plurality of connection nodes, such that:
 the first plurality of switching elements further comprises:
 a third switching element coupled between a fourth of the plurality of connection nodes and one selected from the group consisting of the input, the output, and the first of the plurality of connection nodes; and 
 a fourth switching element coupled between a fifth of the plurality of connection nodes and another selected from the group consisting of the input, the output, and the first of the plurality of connection nodes; and 
 
 the at least one variable shunt capacitance circuit comprises at least three variable shunt capacitance circuits. 
 
     
     
       4. The first RF impedance translation circuit of  claim 2  wherein:
 the first plurality of inductive elements comprises at least three inductive elements cascaded in series without any series switching elements between the input and the output using at least the first of the plurality of connection nodes and a fourth of the plurality of connection nodes; 
 the second plurality of inductive elements comprises at least three inductive elements cascaded in series using the plurality of connection nodes; 
 the first plurality of switching elements further comprises a third switching element coupled between a fifth of the plurality of connection nodes and one selected from the group consisting of the input, the output, the first of the plurality of connection nodes, and the fourth of the plurality of connection nodes; and 
 the at least one variable shunt capacitance circuit comprises at least three variable shunt capacitance circuits. 
 
     
     
       5. The first RF impedance translation circuit of  claim 2  wherein:
 each of at least one of the first plurality of inductive elements comprises a transmission line segment; and 
 each of at least one of the second plurality of inductive elements comprises a transmission line segment. 
 
     
     
       6. The first RF impedance translation circuit of  claim 2  wherein:
 each of at least one of the first plurality of inductive elements comprises a spiral transmission line segment; and 
 each of at least one of the second plurality of inductive elements comprises a spiral transmission line segment. 
 
     
     
       7. The first RF impedance translation circuit of  claim 2  wherein:
 each of at least one of the first plurality of inductive elements comprises a spiral printed circuit board (PCB) trace; and 
 each of at least one of the second plurality of inductive elements comprises a spiral PCB trace. 
 
     
     
       8. The first RF impedance translation circuit of  claim 2  wherein one of the at least one variable shunt capacitance circuit comprises a varactor diode, which provides capacitance based on a direct current (DC) bias voltage, which is based on a corresponding capacitance control signal. 
     
     
       9. The first RF impedance translation circuit of  claim 2  wherein one of the at least one variable shunt capacitance circuit comprises at least one switched capacitive element, such that each switched capacitive element has one of an OFF state and an ON state based on a corresponding capacitance control signal. 
     
     
       10. The first RF impedance translation circuit of  claim 2  wherein the common reference is ground. 
     
     
       11. The first RF impedance translation circuit of  claim 2  adapted to:
 operate in one of a first operating mode and a second operating mode; and 
 operate using a first RF communications band during the first operating mode and operate using a second RF communications band during the second operating mode. 
 
     
     
       12. The first RF impedance translation circuit of  claim 11  wherein:
 the first RF communications band has a first center frequency; and 
 the second RF communications band has a second center frequency, such that a ratio of the first center frequency to the second center frequency is greater than two. 
 
     
     
       13. The first RF impedance translation circuit of  claim 11  wherein the common power amplifier is adapted to provide the RF input signal. 
     
     
       14. The first RF impedance translation circuit of  claim 13  wherein an RF antenna is adapted to receive the RF output signal, such that the first impedance is based on the RF antenna. 
     
     
       15. The first RF impedance translation circuit of  claim 2  wherein an RF antenna is adapted to receive the RF output signal, such that the first impedance is based on the RF antenna. 
     
     
       16. The first RF impedance translation circuit of  claim 15  wherein:
 when the RF antenna has a voltage standing wave ratio (VSWR) of about one-to-one, the second impedance has a first magnitude; and 
 when the RF antenna has a VSWR of about four-to-one, the second impedance has a second magnitude, which is about equal to the first magnitude. 
 
     
     
       17. The first RF impedance translation circuit of  claim 1  wherein when the at least one of the segmented output stages is in the DISABLED state, the second impedance is about matched to the first output impedance and when the at least one of the segmented output stages is in the ENABLED state, the second impedance is about matched to the second output impedance. 
     
     
       18. A first radio frequency (RF) impedance translation circuit comprising:
 a first plurality of capacitive elements cascaded in series without any series switching elements between an input and an output using at least a first of a plurality of connection nodes; 
 a second plurality of capacitive elements cascaded in series using the plurality of connection nodes; 
 a first plurality of switching elements, such that:
 a first of the first plurality of switching elements is coupled between a second of the plurality of connection nodes and one selected from the group consisting of the input, the output, and the first of the plurality of connection nodes; 
 a second of the first plurality of switching elements is coupled between a third of the plurality of connection nodes and another selected from the group consisting of the input, the output, and the first of the plurality of connection nodes; and 
 each of the first plurality of switching elements has one of an OFF state and an ON state based on a switch control signal; 
 
 at least one variable shunt inductance circuit, such that each variable shunt inductance circuit:
 is coupled between a common reference and a corresponding one selected from the group consisting of the input, the output, and the plurality of connection nodes; and 
 has an inductance based on an inductance control signal; and 
 
 control circuitry adapted to provide each inductance control signal to a corresponding each variable shunt inductance circuit and each switch control signal to a corresponding each of the first plurality of switching elements, 
 
       wherein a first impedance presented to the output is translated into a second impedance presented at the input; and further comprising: 
       a common power amplifier comprising a plurality of segmented output stages coupled in parallel, such that:
 when at least one of the segmented output stages is in a DISABLED state, the common power amplifier has a first output power level and a first output impedance; and 
 when the at least one of the segmented output stages is in an ENABLED state, the common power amplifier has a second output power level and a second output impedance, 
 
       wherein the second output power level is greater than the first output power level and the second output impedance is less than the first output impedance. 
     
     
       19. A first differential radio frequency (RF) impedance translation circuit comprising:
 a first plurality of inductive elements cascaded in series without any series switching elements between a non-inverting input and a non-inverting output using at least a first of a first plurality of connection nodes; 
 a second plurality of inductive elements cascaded in series using the first plurality of connection nodes; 
 a third plurality of inductive elements cascaded in series without any series switching elements between an inverting input and an inverting output using at least a first of a second plurality of connection nodes; 
 a fourth plurality of inductive elements cascaded in series using the second plurality of connection nodes; 
 a first plurality of switching elements, such that:
 a first of the first plurality of switching elements is coupled between a second of the first plurality of connection nodes and one selected from the group consisting of the non-inverting input, the non-inverting output, and the first of the first plurality of connection nodes; 
 a second of the first plurality of switching elements is coupled between a third of the first plurality of connection nodes and another selected from the group consisting of the non-inverting input, the non-inverting output, and the first of the first plurality of connection nodes; and 
 each of the first plurality of switching elements has one of an OFF state and an ON state based on a switch control signal; 
 
 a second plurality of switching elements, such that:
 a first of the second plurality of switching elements is coupled between a second of the second plurality of connection nodes and one selected from the group consisting of the inverting input, the inverting output, and the first of the second plurality of connection nodes; 
 a second of the second plurality of switching elements is coupled between a third of the second plurality of connection nodes and another selected from the group consisting of the inverting input, the inverting output, and the first of the second plurality of connection nodes; and 
 each of the second plurality of switching elements has one of an OFF state and an ON state based on a switch control signal; 
 
 at least one variable shunt capacitance circuit, such that each variable shunt capacitance circuit:
 is coupled between a corresponding one selected from a first group consisting of the non-inverting input, the non-inverting output, and the first plurality of connection nodes, and a corresponding one selected from a second group consisting of the inverting input, the inverting output, and the second plurality of connection nodes; and 
 has a capacitance based on a capacitance control signal; and 
 
 control circuitry adapted to provide each capacitance control signal to a corresponding each variable shunt capacitance circuit and each switch control signal to a corresponding each of the first plurality of switching elements or each of the second plurality of switching elements, to provide impedance translation characteristics of the first differential RF impedance translation circuit, 
 
       wherein a first impedance presented between the non-inverting output and the inverting output is translated into a second impedance presented between the non-inverting input and the inverting input.